High levels of abnormal sperm found in SoCal pumas, indicator of inbreeding that shows threat of extinction

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Scientists monitoring two populations of pumas in southern California have discovered the first reproductive signs of inbreeding among them, a finding that reveals a serious threat to their future survival.

It was recently discovered that some of the big cats had, on average, an abnormal sperm count of 93% – the first evidence that inbreeding has an effect on the reproductive system, according to a study conducted by UCLA. This could possibly make it harder for pumas to breed, as the local population faces a lack of genetic diversity, posing a potential threat of extinction.

“This is a serious problem for an animal that is already endangered locally,” Audra Huffmeyer, postdoctoral researcher at UCLA and lead author of the study, said in a press release from the National Park Service. studies fertility in large feline species and is a National Geographic Explorer. “It’s pretty harsh.”

Inbreeding is known to be a problem for cougar populations in the Santa Monica and Santa Ana mountains, with some of the big cats already showing signs such as tail deformities and testicular defects, according to previous research.

The malformed sperm is the latest discovery that reveals the extent of the problems each group faces.

Both populations are locked into their respective mountain ranges by busy freeways in the greater Los Angeles area and Orange and Riverside counties, making it difficult for them to mate with cougars outside of their own. territory.

The National Park Service has studied the inhabitants of the Santa Monica Mountains for about two decades, tagging and tracking more than 100 big cats to date.

The last kittens to be included in the study were a litter of four captured in late November, according to Park Service officials. They were apparently abandoned by their mother, who was not among the wanted pumas.

Currently, more than a dozen pumas are monitored with GPS collars in the Santa Monica Mountains National Recreation Area.

In the past year, researchers have found nine adult males in the Santa Monica and Santa Ana ranges who exhibited symptoms of inbreeding.

Semen samples were also taken from five of the pumas after their deaths (from causes ranging from rat deaths to vehicle impact). Through the samples, the team found that all five had high levels of abnormal sperm.

This early evidence of reduced infertility demonstrates the need for things like wildlife crossings on local freeways, so these animals can roam further into the urban sprawl and expand their pool of potential mates, the statement said.

“If we don’t do anything to introduce more genetic diversity into the mountain lions of southern California, we’ll have more males with reproductive issues, fewer kittens, and a lower survival rate,” Huffmeyer said in the communicated.

“If we don’t do anything to add genetic diversity, the end is near,” she added. “It sounds dramatic, but that’s what we saw.”

A major problem is that few pumas have made it through busy highways such as the 101 and 405, as well as other local roads. Vehicle crashes have been one of the leading killers of the puma population in the Santa Monica Mountains.

Among the good news for the species, Caltrans is expected to inaugurate a wildlife bridge this month over Highway 101 in the Agoura Hills area. And a possible intersection on Highway 15 in Riverside County is also in the early stages of planning, NPS officials said.

But without sustained action, scientists predict that big cats could potentially become extinct in Southern California’s two mountain ranges within this century.

“Although they haven’t seen any evidence yet, once scientists start to discover significant inbreeding depression – which means decreased fertility and kitten survival – extinction is expected to occur in the 50-year-olds, with a median extinction time of 12 to 15 years, “the statement said. , citing research articles from 2016 and 2019.

The study is expected to be published this month in the journal Theriogenology but can currently be viewed online here.

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